Monovalent anti-cd3 adjuvants

ABSTRACT

This document provides methods and materials related to using monovalent anti-CD3 antibodies (e.g., monovalent anti-CD3 Fab fragments) as adjuvants to increase the immune response produced against an antigen (e.g., a tumor associated antigen). For example, vaccine compositions containing monovalent anti-CD3γε Fab fragments in combination with tumor associated antigens (e.g., tumor associated antigens having little or no immunogenicity in the absence of monovalent anti-CD3γε Fab fragments) alone or in combination with adjuvants for signals two and/or three required for full activation of T cell immune function, as well as methods and materials for using monovalent anti-CD3γε Fab fragments to increase the immune response produced against an antigen (e.g., a tumor associated antigen) within a mammal (e.g., a human) are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 14/571,601, filed Dec. 16, 2014, which claims the benefit of U.S. Provisional Application Ser. No. 61/918,545, filed Dec. 19, 2013. The disclosures of the prior applications are considered part of (and are incorporated by reference in) the disclosure of this application.

STATEMENT AS TO FEDERALLY SPONSORED RESEARCH

This invention was made with government support under AI097187 awarded by National Institutes of Health. The government has certain rights in the invention.

BACKGROUND

1. Technical Field

This document provides methods and materials related to using monovalent anti-CD3 antibodies (e.g., monovalent anti-CD3 Fab fragments) as adjuvants to increase the immune response produced against an antigen (e.g., a tumor associated antigen). For example, this document provides monovalent anti-CD3γε Fab fragments and vaccine compositions containing monovalent anti-CD3γε Fab fragments in combination with tumor associated antigens (e.g., tumor associated antigens having little or no immunogenicity in the absence of monovalent anti-CD3γε Fab fragments) as well as methods and materials for using monovalent anti-CD3γε Fab fragments to increase the immune response produced against an antigen (e.g., a tumor associated antigen) within a mammal (e.g., a human).

2. Background Information

Cancer is one of the leading causes of death in the world, responsible of about 13 percent of all human deaths. In spite of the significant advances achieved during recent decades, the efficiency of cancer treatments remains rather poor. Unfortunately, main treatments like radio- and chemotherapy do not specifically target cancer cells, damaging healthy tissues as well. As a result, these kinds of cancer therapies themselves cause significant morbidity and mortality. On the other hand, these treatments frequently fail to eradicate cancer cells efficiently, leading to cancer recurrence.

Immunotherapy is an attractive alternative to treat cancer. The immune system has the capacity to identify cancer cells specifically, sparing healthy tissue from its attack. The main goal when stimulating the immune system against a tumor using vaccination strategies is to achieve an efficient anti-tumor T cell response that not only is specific for the cancer but also develops memory to control potential recurrence. T cell activation depends on T cells receiving three signals. Signal one consists of the recognition by the T cell receptor (TCR) of a foreign antigen in the shape of a peptide/MHC on the surface of professional antigen presenting cells (APCs). Co-stimulatory molecules on the APCs and their corresponding receptors in T cells provide signal two. Signal three is provided by soluble cytokines present in the T cell milieu.

Tumor associated antigens (TAA) come from mutated self-proteins, over/aberrantly expressed self-proteins, or unique foreign proteins from oncoviruses that are expressed by tumor cells. When mutated or from viral origin, tumor proteins might generate unique TAAs that can stimulate the TCR efficiently. However, in most cases, TAAs are closely related with self-proteins and are not very efficient in providing signal one. Some immunotherapies focus on the development of anti-tumor vaccines that incorporate the use of adjuvants that function to increase the efficiency of signals two and three such as toll like receptor ligands (e.g., CpG and MLP), cytokines, (e.g., IL-2, IL-12, and IFNα/β, and chemokines (e.g., GM-CSF).

The option to improve the poorly immunogenic nature of most TAAs is reduced to a strategy of vaccinating mammals with altered peptide ligands (APLs). In an attempt to compensate for the weakness of signal one provided by TAAs, the sequence of the natural tumor peptide is modified to increase its affinity for the MHC and/or the TCR, with the expectation that the immunogenicity of the resulting APL will be higher than the natural TAA. This strategy, however, can be limited by the fact that once the natural tumor peptide is modified, (i) the TCRs stimulated by the APLs may not be specific to the natural TAAs from the tumor, (ii) the T cells may become anergized by the natural TAAs from the tumor, and/or (iii) the TCRs may be specific for other tissues, thereby displaying undesired side effects.

SUMMARY

This document provides methods and materials related to using monovalent anti-CD3 antibodies (e.g., monovalent anti-CD3 Fab fragments) as adjuvants to increase the immune response produced against an antigen (e.g., a tumor associated antigen). For example, this document provides monovalent anti-CD3γε Fab fragments as well as vaccine compositions containing monovalent anti-CD3γε Fab fragments in combination with tumor associated antigens. In some cases, the tumor associated antigen can be an antigen having little or no immunogenicity in the absence of monovalent anti-CD3γε Fab fragments. This document also provides methods and materials for using monovalent anti-CD3γε Fab fragments to increase the immune response produced against an antigen (e.g., a tumor associated antigen) within a mammal (e.g., a human).

As described herein, monovalent anti-CD3γε Fab fragments can be used to increase the immune response produced against an antigen (e.g., a tumor associated antigen). For example, monovalent anti-CD3γε Fab fragments provided herein can be used to increase the immunogenicity of natural TAAs without having to change their peptide sequences. In some cases, a monovalent anti-CD3γε Fab fragment provided herein can be used to increase the immunogenicity of a natural TAA, an APL, a mixture of different TAAs, a mixture of different APLs, or a mixture of TAAs and APLs. In some cases, a monovalent anti-CD3γε Fab fragment provided herein can be used to increase the immunogenicity of tumor associated antigens in the form of a tumor cell lysate. For example, monovalent anti-CD3γε Fab fragments provided herein can be combined with a tumor cell lysate to produce a mixture that is more immunogenic than the tumor cell lysate alone. In some cases, the monovalent anti-CD3γε Fab fragments provided herein can be used in combination with tumor associated antigens and other particular adjuvants designed to increase signal two and/or signal three of T cell activation.

In general, one aspect of this document features a method for increasing an immune response against an antigen. The method comprises, or consists essentially of, administering a composition comprising a monovalent anti-CD3γε antibody preparation and the antigen or nucleic acid that expresses the antigen to a mammal, wherein the monovalent anti-CD3γε antibody preparation comprises Fab fragments of an anti-CD3γε antibody, and wherein the mammal produces an immune response against the antigen that is increased as compared to an immune response produced against the antigen when the antigen or the nucleic acid is administered to a comparable mammal in the absence of the monovalent anti-CD3γε antibody preparation. The mammal can be a human, and the Fab fragments can be Fab fragments of an anti-human CD3γε antibody. The Fab fragments can be Fab fragments of a humanized anti-human CD3γε antibody. The Fab fragments can be Fab fragments of a fully human anti-human CD3γε antibody. The antigen can be a tumor associated antigen. The tumor associated antigen can be a polypeptide. The antigen can be within an extract from a whole tumor cell lysate. The method can comprise administering the antigen to the mammal. The method can comprise administering the nucleic acid to the mammal.

In another aspect, this document features a method for increasing an immune response against a cancer antigen. The method comprises, or consists essentially of, administering a composition comprising a monovalent anti-CD3γε antibody preparation to a mammal having cancer cells, wherein the monovalent anti-CD3γε antibody preparation comprises Fab fragments of an anti-CD3γε antibody, and wherein the mammal produces an immune response against the antigen that is increased as compared to an immune response produced against the cancer antigen in a comparable mammal not administered the monovalent anti-CD3γε antibody preparation. The mammal can be a human, and the Fab fragments can be Fab fragments of an anti-human CD3γε antibody. The Fab fragments can be Fab fragments of a humanized anti-human CD3γε antibody. The Fab fragments can be Fab fragments of a fully human anti-human CD3γε antibody. The antigen can be a tumor associated antigen. The tumor associated antigen can be a polypeptide. The antigen can be within an extract from a whole tumor cell lysate. The method can comprise administering the antigen to the mammal. The method can comprise administering nucleic acid encoding the antigen to the mammal. The method can comprise administering tumor specific cytotoxic T lymphocytes to the mammal. The method can comprise administering an IL-2 polypeptide to the mammal.

In another aspect, this document features a method for increasing an immune response against an antigen. The method comprises, or consists essentially of, administering a composition comprising a monovalent anti-CD3γε antibody preparation and tumor specific cytotoxic T lymphocytes, wherein the monovalent anti-CD3γε antibody preparation comprises Fab fragments of an anti-CD3γε antibody, and wherein the mammal produces an immune response against the antigen that is increased as compared to an immune response produced against the antigen when the tumor specific cytotoxic T lymphocytes are administered to a comparable mammal in the absence of the monovalent anti-CD3γε antibody preparation. The mammal can be a human, and the Fab fragments can be Fab fragments of an anti-human CD3γε antibody. The Fab fragments can be Fab fragments of a humanized anti-human CD3γε antibody. The Fab fragments can be Fab fragments of a fully human anti-human CD3γε antibody. The antigen can be a tumor associated antigen. The tumor associated antigen can be a polypeptide. The method can comprise administering the antigen to the mammal. The method can comprise administering a nucleic acid encoding the antigen to the mammal. The method can comprise administering an IL-2 polypeptide to the mammal.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although methods and materials similar or equivalent to those described herein can be used to practice the invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a T cell receptor/CD3 complex of a T cell that is in the closed conformation.

FIG. 2 is a diagram of a T cell receptor/CD3 complex of a T cell that is in an open conformation (CD3Δc), which can be induced by the binding of a peptide/MHC complex.

FIG. 3 is a diagram of a CD3 pull down (CD3-PB) assay using Nck-SH3.1 beads and a western blot with anti-CD3ζ antibodies.

FIG. 4 contains a diagram (left) of how an APA 1/1 antibody to the cytoplasmic tail of CD3ε blocks the pull down of Nck SH3.1, and a diagram (right) of how an 2C11 antibody to an extracellular domain of CD3ε promotes the open conformation allowing detection by the pull down of Nck SH3.1.

FIG. 5 is a diagram of a T cell receptor/CD3 complex in an open conformation (CD3Δc) along with a list of properties.

FIG. 6 contains a diagram (left) of how poorly immunogenic or non-immunogenic antigens in combination with MHC molecules do not result in the CD3Δc conformation, and a diagram (right) of how immunogenic antigens in combination with MHC molecules do result in the CD3Δc conformation.

FIG. 7 contains a diagram of how most TAA are poorly immunogenic or non-immunogenic antigens that when in combination with MHC molecules do not result in the CD3Δc conformation.

FIG. 8 contains a diagram representing how a soluble agent can produce the open CD3Δc conformation even though a poorly immunogenic or non-immunogenic antigen in combination with an MHC molecule is engaging the T cell receptor/CD3 complex.

FIG. 9 contains a diagram of a monovalent anti-CD3γε Fab fragment (e.g., Mono-7D6-Fab) bound to the extracellular domains of CD3γε in a manner that triggers the open CD3Δc conformation.

FIG. 10 contains a schematic diagram and graph showing the digestion of the 7D6 monoclonal antibody into Fab and Fc fragments.

FIG. 11 contains graphs demonstrating that Mono-7D6-Fab binds to the T cell receptor and does not block the binding of peptide/MHC complexes (pMHC7) to T cell receptors. Ms IgG Fab is a non-specific Fab control for Mono-7D6-Fab.

FIG. 12 is a western blot demonstrating that Mono-7D6-Fab induces the open CD3Δc conformation in mature T cells obtained from mice.

FIG. 13 contains graphs demonstrating that Mono-7D6-Fab alone does not stimulate T cells.

FIG. 14 is a graph listing various altered peptide ligands (APLs) derived from the OVA polypeptide (pOVA) and their levels of immunogenicity.

FIG. 15 contains graphs plotting the percent of CD69+ or CD25+ OT-I T cells following exposure to T2-Kb antigen presenting cells (APCs) having H2-Kb MHC-I molecules loaded with the indicated OVA APLs plus either control Fab IgG from mouse (Ig Fab; 5 μg/mL) or Mono-7D6-Fab (5 μg/mL).

FIG. 16 contains graphs plotting the percent OT-I T cells dividing (M3%) following exposure to T2-Kb antigen presenting cells (APCs) having MHC-I molecules loaded with the indicated OVA APLs plus either control Fab IgG from mouse (Ig Fab; 5 μg/mL) or Mono-7D6-Fab (5 μg/mL).

FIG. 17 is a bar graph plotting the percent of OT-I CTL specific killing of EL-4 tumor target cells when incubated in the presence of 2 μM of the indicated OVA APLs with either control Fab IgG from mouse (Ig Fab; 5 μg/mL) or Mono-7D6-Fab (5 μg/mL). The OT-I T cell to target cell ratio was 10:1.

FIG. 18 is a bar graph plotting the levels of indicated cytokines in blood serum from healthy mice at day 7 following intravenous injections of either control Ms Ig Fab; (10 μg/mouse) or Mono-7D6-Fab (10 μg/mouse) on days 1, 3, 5, and 7. Staphylococcal enterotoxin B (SEB) was used as a positive control for an autoimmune response that produces a specific cytokine profile tested in this experiment.

FIG. 19 contains photographs of liver and kidney tissue from the mice tested in FIG. 18 (3 mice injected with Mouse Ig Fab, 10 μg/mouse; or Mono-7D6-Fab, 10 μg/mL) demonstrating that Mono-7D6-Fab does not cause signs of an autoimmune response in the shape of tissue inflammation.

FIG. 20 is a western blot of a CD3 pull down (CD3-PD) assay using Pmel TCR transgenic CD8+ T cells that are specific for the natural/weak tumor antigen mouse gp100 (mg100). Pmel T cells were either treated with a non-specific Ig (Ig) or with the antigens mg100 or hgp100 (xenogeneic variant of mg100 from human melanocytes that functions as a strong antigen for Pmel TCR) for 1 hour at 37° C. Then, Pmel T cells were lysed, and the resulting samples were used to detect CD3 open conformation using the CD3-PD assay as described herein. The western blot revealed that while the strong/xenogeneic variant hgp100 induces CD3Δc (6 fold induction of open-CD3), the weak/natural melanoma antigen mgp100 fails to induce CD3Δc.

FIG. 21 contains a set of photographs of lung tissue from mice injected with B16.F10 tumor cells on day 0 and treated intravenously with mouse Ig Fab (10 μg/mouse on day 0) or Mono-7D6-Fab (10 μg/mouse on day 0). On day 21, the lungs were extracted and evaluated for the presence of metastatic melanoma tumor burden. Less melanoma burden was observed in mice treated with Mono-7D6-Fab. The two dot-plots present two different means of objective melanoma quantification in the lungs of each group of mice. On the left plot, melanoma density was quantified using software that detects dark melanoma tissue in the lungs. On the right plot, lung weight was plotted to reflect the amount of melanoma burden. Both plots reveal a statistical difference in the melanoma burden between the mouse IgG Fab treated mice (higher burden) and the Mono-7D6-Fab treated mice (lower burden).

FIG. 22 contains photographs of lung tissue from mice lacking T cells (CD3εζ^(−/−) mice) injected with B16.F10 tumor cells on day 0 and treated intravenously with mouse Ig Fab; (10 μg/mouse on day 0) or Mono-7D6-Fab (10 μg/mouse on day 0). On day 21, the lungs were extracted and evaluated for the presence of metastatic melanoma tumor burden. Similar tumor burden was observed in both treatment groups, demonstrating that T cells are required for the response observed in FIG. 21. On the left, there is an objective quantification of tumor burden in lung of mice of each group treatment using a dot plot that depicts melanoma density as specified in FIG. 21. There is not a statistical difference in the melanoma burden between the mouse IgG Fab treated mice and the Mono-7D6-Fab treated mice.

FIG. 23 contains a dot plot to quantify melanoma burden and photographs of lung tissue from mice with T cells (No Depl), without CD4 T cells (CD4 Depl; CD4 T cells were depleted by injecting anti-CD4 specific antibody), or without CD8 T cells (CD8 Depl; CD8 T cells were depleted by injecting anti-CD8 specific antibody) injected with B16.F10 tumor cells on day 0 and treated intravenously with either mouse IgG Fab; (10 μg/mouse on day 0) or Mono-7D6-Fab (10 μg/mouse on day 0). On day 21, the lungs were extracted and evaluated for the presence of metastatic melanoma tumor burden and quantified as descried in FIGS. 21 and 22. The results demonstrate that both CD4 and CD8 T cells are required for the full anti-melanoma effect of Mono-7D6-Fab treatment observed when both CD4 and CD8 T cells are not depleted.

FIG. 24 contains photographs of lung tissue from OT-I Rag2 KO mice. In these mice, the only kind of T cells present are OT-I CD8 T cells specific for an antigen from chicken ovalbumin. Therefore, these T cells are incapable of recognizing any antigens from the B16F10 melanoma tumor. All the OT-I mice were injected with B16.F10 tumor cells on day 0 and treated intravenously with mouse Ig Fab (10 μg/mouse on day 0) or Mono-7D6-Fab (10 μg/mouse on day 0). On day 21, the lungs were extracted and evaluated for the presence of metastatic melanoma tumor burden. Similar tumor burden was observed in both treatment groups, demonstrating that Mono-7D6-Fab treatment requires the presence of CD8 T cells specific for the tumor antigens to exert its anti-tumor effect. On the left, there is an objective quantification of tumor burden in lung of OT-I mice of each treatment group using a dot plot that depicts melanoma density, as specified in FIG. 20. There is not a statistical difference in the melanoma burden between the mouse IgG Fab treated mice and the Mono-7D6-Fab treated OT-I mice.

FIGS. 25A-E. Mono-7D6-Fab promotes therapeutic anti-tumor T cell responses in the B16F10/B6 lung metastatic melanoma model when administered three days after tumor injection. FIG. 25A is a schematic summary of the experimental procedure. FIG. 25B contains photographs of the lungs that were evaluated for the presence of metastatic melanoma tumor burden. FIG. 25C is a graph plotting melanoma density for mice treated with the indicated Fab (t test, ***p<0.0001). FIG. 25D is a graph plotting the percent of T cells positive for CD107a. FIG. 25E is a graph plotting the percent of T cells positive for CD44 and CD62L.

FIGS. 26A-D. Anti-melanoma effect when Mono-7D6-Fab therapy is combined with adoptive transfer of melanoma specific cytotoxic lymphocytes. FIG. 26A is a schematic summary of the experimental procedure. FIG. 26B contains photographs of the lungs that were evaluated for the presence of metastatic melanoma tumor burden. FIG. 26C is a graph plotting melanoma density for mice treated with the indicated Fab and CTLs. FIG. 26D is a graph plotting the number of CD8 T cells from mediastinal lymph node or lung that stained with the Kd-tetramer gp100 to identify cells specific for the melanoma antigen gp100.

DETAILED DESCRIPTION

This document provides methods and materials related to monovalent anti-CD3γε antibodies (e.g., monovalent anti-CD3 Fab fragments). For example, this document provides monovalent anti-CD3γε antibody preparations, methods for making monovalent anti-CD3γε antibody preparations, and methods for using monovalent anti-CD3γε antibody preparations as adjuvants to increase the immune response produced against an antigen (e.g., a tumor associated antigen). For example, this document provides monovalent anti-CD3γε Fab fragments as well as vaccine compositions containing monovalent anti-CD3γε Fab fragments in combination with tumor associated antigens. In some cases, the tumor associated antigen can be an antigen having little or no immunogenicity in the absence of monovalent anti-CD3γε Fab fragments. This document also provides methods and materials for using monovalent anti-CD3γε Fab fragments to increase the immune response produced against an antigen (e.g., a tumor associated antigen) within a mammal (e.g., a human).

In some cases, a monovalent anti-CD3γε antibody preparation provided herein can bind to a CD3γε dimer with little or no detectable binding to a CD3E polypeptide not in the form of a CD3γε dimer and with little or no detectable binding to a CD3γ polypeptide not in the form of a CD3γε dimer. For example, a monovalent anti-CD3γε antibody preparation provided herein can bind to a human CD3γε dimer with little or no detectable binding to a human CD3ε polypeptide not in the form of a CD3γε dimer and with little or no detectable binding to a human CD3γ polypeptide not in the form of a CD3γε dimer. An example of an antibody having the ability to bind to a CD3γε dimer with little or no detectable binding to a CD3ε polypeptide not in the form of a CD3γε dimer and with little or no detectable binding to a CD3γ polypeptide not in the form of a CD3γε dimer includes, without limitation, the 7D6 antibody described elsewhere (Van Snick et al., Eu. J. Immunol., 21:1703-1709 (1991)). Fab fragments from such an antibody can be used to obtain monovalent anti-CD3γε antibodies (e.g., monovalent anti-CD3γε Fab fragments). The term “antibody” as used herein refers to intact antibodies as well as antibody fragments that retain some ability to bind an epitope. Such fragments include, without limitation, Fab, F(ab′)2, and Fv antibody fragments. The term “epitope” refers to an antigenic determinant on an antigen to which the paratope of an antibody binds. Epitopic determinants usually consist of chemically active surface groupings of molecules (e.g., amino acid or sugar residues) and usually have specific three dimensional structural characteristics as well as specific charge characteristics.

The antibodies provided herein that can be used to make a monovalent anti-CD3γε Fab fragments provided herein can be any antibody (e.g., a monoclonal antibody) having binding affinity (e.g., specific binding affinity) for a CD3γε dimer with little or no detectable binding to a CD3E polypeptide not in the form of a CD3γε dimer or a CD3γ polypeptide not in the form of a CD3γε dimer. For example, a monovalent anti-CD3γε antibody preparation can be a preparation of Fab fragments having the ability to bind to a CD3γε dimer with little or no detectable binding to a CD3ε polypeptide not in the form of a CD3γε dimer and with little or no detectable binding to a CD3γ polypeptide not in the form of a CD3γε dimer.

Any appropriate method can be used to produce Fab fragments from intact antibodies. For example, standard papain digestion methods can be used to make an Fab antibody preparation. In some cases, a monovalent anti-CD3γε antibody preparation provided herein can be a preparation of Fab fragments of humanized or fully-human anti-human CD3γε dimer antibodies. In some cases, a monovalent anti-CD3γε antibody preparation provided herein (e.g., a monovalent anti-CD3γε antibody preparation containing Fab fragments of a humanized anti-CD3γε antibody) can have the ability to increase the immune response produced against an antigen (e.g., a tumor associated antigen).

Antibodies provided herein can be prepared using any appropriate method. For example, a sample containing a CD3γε dimer (e.g., a human CD3γε dimer or a chimeric mouse/human CD3γε dimer) can be used as an immunogen to elicit an immune response in an animal such that specific antibodies are produced. The immunogen used to immunize an animal can be chemically synthesized or derived from translated cDNA. In some cases, cells (e.g., mouse T cells) transfected to express a CD3γε dimer (e.g., a human CD3γε dimer or a chimeric mouse/human CD3γε dimer) can be used as an immunogen. In some cases, the immunogen can be conjugated to a carrier polypeptide, if desired. Commonly used carriers that are chemically coupled to an immunizing polypeptide include, without limitation, keyhole limpet hemocyanin (KLH), thyroglobulin, bovine serum albumin (BSA), and tetanus toxoid.

The preparation of polyclonal antibodies is well-known to those skilled in the art. See, e.g., Green et al., Production of Polyclonal Antisera, in IMMUNOCHEMICAL PROTOCOLS (Manson, ed.), pages 1 5 (Humana Press 1992) and Coligan et al., Production of Polyclonal Antisera in Rabbits, Rats, Mice and Hamsters, in CURRENT PROTOCOLS IN IMMUNOLOGY, section 2.4.1 (1992). In addition, those of skill in the art will know of various techniques common in the immunology arts for purification and concentration of polyclonal antibodies, as well as monoclonal antibodies (Coligan et al., Unit 9, Current Protocols in Immunology, Wiley Interscience, 1994).

The preparation of monoclonal antibodies also is well-known to those skilled in the art. See, e.g., Kohler & Milstein, Nature 256:495 (1975); Coligan et al., sections 2.5.1 2.6.7; and Harlow et al., ANTIBODIES: A LABORATORY MANUAL, page 726 (Cold Spring Harbor Pub. 1988). Briefly, monoclonal antibodies can be obtained by injecting mice with a composition comprising an antigen, verifying the presence of antibody production by analyzing a serum sample, removing the spleen to obtain B lymphocytes, fusing the B lymphocytes with myeloma cells to produce hybridomas, cloning the hybridomas, selecting positive clones that produce antibodies to the antigen, and isolating the antibodies from the hybridoma cultures. Monoclonal antibodies can be isolated and purified from hybridoma cultures by a variety of well established techniques. Such isolation techniques include affinity chromatography with Protein A Sepharose, size exclusion chromatography, and ion exchange chromatography. See, e.g., Coligan et al., sections 2.7.1 2.7.12 and sections 2.9.1 2.9.3; Barnes et al., Purification of Immunoglobulin G (IgG) , in METHODS IN MOLECULAR BIOLOGY, VOL. 10, pages 79 104 (Humana Press 1992).

In addition, methods of in vitro and in vivo multiplication of monoclonal antibodies are well known to those skilled in the art. Multiplication in vitro can be carried out in suitable culture media such as Dulbecco's Modified Eagle Medium or RPMI 1640 medium, optionally replenished by mammalian serum such as fetal calf serum, or trace elements and growth sustaining supplements such as normal mouse peritoneal exudate cells, spleen cells, and bone marrow macrophages. Production in vitro provides relatively pure antibody preparations and allows scale up to yield large amounts of the desired antibodies. Large scale hybridoma cultivation can be carried out by homogenous suspension culture in an airlift reactor, in a continuous stirrer reactor, or in immobilized or entrapped cell culture. Multiplication in vivo may be carried out by injecting cell clones into mammals histocompatible with the parent cells (e.g., osyngeneic mice) to cause growth of antibody producing tumors. Optionally, the animals are primed with a hydrocarbon, especially oils such as pristane (tetramethylpentadecane) prior to injection. After one to three weeks, the desired monoclonal antibody is recovered from the body fluid of the animal. In some cases, the antibodies provided herein can be made using non-human primates. General techniques for raising therapeutically useful antibodies in baboons can be found, for example, in Goldenberg et al., International Patent Publication WO 91/11465 (1991) and Losman et al., Int. J. Cancer, 46:310 (1990).

In some cases, the antibodies can be humanized monoclonal antibodies. Humanized monoclonal antibodies can be produced by transferring mouse complementarity determining regions (CDRs) from heavy and light variable chains of the mouse immunoglobulin into a human variable domain, and then substituting human residues in the framework regions of the murine counterparts. The use of antibody components derived from humanized monoclonal antibodies obviates potential problems associated with the immunogenicity of murine constant regions when treating humans. General techniques for cloning murine immunoglobulin variable domains are described, for example, by Orlandi et al., Proc. Nat'l. Acad. Sci. USA 86:3833 (1989). Techniques for producing humanized monoclonal antibodies are described, for example, by Jones et al., Nature 321:522 (1986); Riechmann et al., Nature 332:323 (1988); Verhoeyen et al., Science 239:1534 (1988); Carter et al., Proc. Nat'l. Acad. Sci. USA 89:4285 (1992); and Sandhu, Crit. Rev. Biotech. 12:437 (1992); Singer et al., J. Immunol. 150:2844 (1993). In some cases, humanization such as super humanization can be used as described elsewhere (Hwang et al., Methods, 36:35-42 (2005)). In some cases, SDR grafting (Kashmiri et al., Methods, 36:25-34 (2005)), human string content optimization (Lazar et al., Mol. Immunol., 44:1986-1998 (2007)), framework shuffling (Dall'Acqua et al., Methods, 36:43-60 (2005); and Damschroder et al., Mol. Immunol., 44:3049-3060 (2007)), and phage display approaches (Rosok et al., J. Biol. Chem., 271:22611-22618 (1996); Radar et al., Proc. Natl Acad. Sci. USA, 95:8910-8915 (1998); and Huse et al., Science, 246:1275-1281 (1989)) can be used to obtain anti-CD3γε antibody preparations. In some cases, fully human antibodies can be generated from recombinant human antibody library screening techniques as described elsewhere (Griffiths et al., EMBO 1, 13:3245-3260 (1994); and Knappik et al., J. Mol. Biol., 296:57-86 (2000)).

Antibodies provided herein can be derived from human antibody fragments isolated from a combinatorial immunoglobulin library. See, for example, Barbas et al., METHODS: A COMPANION TO METHODS IN ENZYMOLOGY, VOL. 2, page 119 (1991) and Winter et al., Ann. Rev. Immunol. 12: 433 (1994). Cloning and expression vectors that are useful for producing a human immunoglobulin phage library can be obtained, for example, from STRATAGENE Cloning Systems (La Jolla, Calif.).

In addition, antibodies provided herein can be derived from a human monoclonal antibody. Such antibodies can be obtained from transgenic mice that have been “engineered” to produce specific human antibodies in response to antigenic challenge. In this technique, elements of the human heavy and light chain loci are introduced into strains of mice derived from embryonic stem cell lines that contain targeted disruptions of the endogenous heavy and light chain loci. The transgenic mice can synthesize human antibodies specific for human antigens and can be used to produce human antibody secreting hybridomas. Methods for obtaining human antibodies from transgenic mice are described by Green et al. (Nature Genet., 7:13 (1994)), Lonberg et al. (Nature, 368:856 (1994)), and Taylor et al. (Int. Immunol., 6:579 (1994)).

Antibody fragments can be prepared by proteolytic hydrolysis of an intact antibody or by the expression of a nucleic acid encoding the fragment. Antibody fragments can be obtained by pepsin or papain digestion of intact antibodies by conventional methods. For example, Fab fragments can be produced by enzymatic cleavage of antibodies with papain. In some cases, antibody fragments can be produced by enzymatic cleavage of antibodies with pepsin to provide a 5S fragment denoted F(ab')₂. This fragment can be further cleaved using a thiol reducing agent, and optionally a blocking group for the sulfhydryl groups resulting from cleavage of disulfide linkages, to produce 3.5S Fab' monovalent fragments. In some cases, an enzymatic cleavage using pepsin can be used to produce two monovalent Fab' fragments and an Fc fragment directly. These methods are described, for example, by Goldenberg (U.S. Pat. Nos. 4,036,945 and 4,331,647). See also Nisonhoff et al., Arch. Biochem. Biophys. 89:230 (1960); Porter, Biochem. J. 73:119 (1959); Edelman et al., METHODS IN ENZYMOLOGY, VOL. 1, page 422 (Academic Press 1967); and Coligan et al. at sections 2.8.1 2.8.10 and 2.10.1 2.10.4.

Other methods of cleaving antibodies, such as separation of heavy chains to form monovalent light heavy chain fragments, further cleavage of fragments, or other enzymatic, chemical, or genetic techniques may also be used provided the fragments retain some ability to bind (e.g., selectively bind) its epitope.

The antibodies provided herein can be substantially pure. The term “substantially pure” as used herein with reference to an antibody means the antibody is substantially free of other polypeptides, lipids, carbohydrates, and nucleic acid with which it is naturally associated. Thus, a substantially pure antibody is any antibody that is removed from its natural environment and is at least 60 percent pure. A substantially pure antibody can be at least about 65, 70, 75, 80, 85, 90, 95, or 99 percent pure.

As described herein, the monovalent anti-CD3γε Fab fragments provided herein can be used to increase the immune response produced against an antigen. Examples of such antigens include, without limitation, germ cell-cancer associated tumor antigens, tumor antigens derived from genetic mutations and atypical gene products, tumor differentiation antigens, and tumor polypeptide ligands. Antigens (e.g., tumor associated antigens) can be administered as, for example, polypeptides (e.g., short or truncated polypeptides or full length polypeptides), DNA encoding such polypeptides, viral particles designed to express such polypeptides, extracts from whole tumor cell lysates, or dendritic cells loaded with such polypeptides or tumor cell lysates. Examples of tumor polypeptide ligands include, without limitation, altered peptide ligands (APLs), xenogeneic tumor peptides, and heteroclitic tumor peptides.

In some cases, a monovalent anti-CD3γε Fab fragment provided herein can be combined with one or more antigens to produce a vaccine composition. For example, a monovalent anti-human CD3γε Fab fragment preparation can be combined with a tumor associated antigen such as whole tumor protein, whole tumor cell lysate, or an altered, xenogeneic, orheteroclitic tumor peptides derived from a whole tumor protein to produce a vaccine composition capable of producing an immune response against tumor cells that is increased in comparison to a comparable vaccine composition lacking monovalent anti-human CD3γε Fab fragments.

In some cases, a monovalent anti-CD3γε Fab fragment provided herein can be used to increase the immunogenicity of tumor associated antigens provided in the form of a tumor cell lysate. For example, monovalent anti-CD3γε Fab fragments provided herein can be combined with a tumor cell lysate to produce a mixture or vaccine composition that is more immunogenic than the tumor cell lysate alone.

In some cases, a vaccine composition can include additional components such as adjuvants designed to increase signal two and/or signal three of T cell activation. Examples of adjuvants designed to increase signal two of T cell activation include, without limitation, Freund's adjuvants and Toll like receptor ligands (like LPS, CpG, and PolyI:C). Examples of adjuvants designed to increase signal three of T cell activation include, without limitation, cytokines (IL-2, IL-12, IFNα, or IFNβ), and chemokines (GM-CFS).

In some cases, a human monovalent CD3εγ-Fab preparation specific for human T cells can be used as an adjuvant to increase the immunogenicity of natural TAAs. Such a human reagent can allow the development of tumor vaccines using natural TAA avoiding the problems related with anti-tumor vaccines: limited repertoire of TAAs immunogenic enough to be considered for the development the vaccine, very intricate design of APLs derived from the analogue natural TAAs to achieve higher affinity for MHC and/or TCR molecules, high risk of stimulating a T cell repertoire not specific for the natural TAAs when using such APLs, together with high risk of promoting adverse effects of stimulated T cell repertoire by the vaccine, and the need to personalize the selection of APLs used to immunize. Additionally, using a human monovalent CD3εγ-Fab preparation to boost natural TAA immunogenicity can be compatibility with: (i) vaccines using single TAAs, TAAs mixtures or tumor lysates as a source of tumor antigenic specificity; or (ii) any existing or new adjuvants designed to increase signal two and/or three to stimulate T cells.

The invention will be further described in the following examples, which do not limit the scope of the invention described in the claims.

EXAMPLES Example 1 Using Monovalent Anti-CD3γε Dimer Fab Fragments as Adjuvants to Increase Immunogenicity

Mono-7D6-Fab specific for mouse T cells was capable of increasing the immunogenicity of antigens that are weak and poorly immunogenic (FIGS. 8-9). Mono-7D6-Fab is a monovalent Fab fragment specific for the CD3εγ dimer of the CD3 complex (FIGS. 1, 9, and 10). The following was performed to confirm the ability of Mono-7D6-Fab to increase the immunogenicity of antigens in the context of cancer disease using a mouse model of lung metastatic melanoma (FIGS. 20-24).

Poorly immunogenic antigens failed to stimulate T cells due to their incompetence to induce a conformational change in the CD3 complex (CD3Δc) (FIGS. 6-7). See, also, Gil et al., J. Immunol., 180(6):3900-9 (2008)). The CD3 complex is a group of trans-membrane proteins associated to the T cell antigen receptor (TCR) that are in charge of starting the process of T cell stimulation once the TCR interacts with a given antigen (FIG. 1). The TCR distinguishes the quality of different antigens in order to instruct the activation of immune function. The most upstream marker currently known to be uniformly indicative of T cell stimulatory antigen recognition is CD3Δc (FIG. 2). CD3Δc has the following attributes (FIGS. 2, 5, and 6): (i) it uncovers a cryptic proline rich sequence (PRS) in CD3ε that is a binding site for specific SH3 domains of several cytoplasmic proteins, including Nck; (ii) it is induced by either anti-TCR/CD3 antibodies, anti-CD3 Fab fragments, or antigenic peptide-MHC ligands; (iii) it occurs earlier than (and is independent of) TCR/CD3 crosslinking and src-kinase activity; (iv) when tested as an isolated variable, CD3Δc is required for optimal T cell signaling and immune function. Considering these observations together, CD3Δc marks an initial communication to CD3 that a signaling-relevant peptide/MHC ligand has been bound by TCR. In mature T cells, weak peptide/MHC ligands fail to induce CD3Δc (FIG. 6). See, also, Gil et al., J. Immunol., 180(6):3900-9 (2008)). Most tumor-associated antigens (TAA) are poorly immunogenic and do not stimulated anti-tumor T cell function. It was hypothesized that most natural TAA fail to induce a T cell immune response due to their failure to induce CD3Δc (FIG. 7). Poorly immunogenic TAA from melanoma like mouse gp100, indeed failed to induce CD3Δc (FIG. 20). Mono-7D6-Fab was tested as a means to provide CD3Δc in trans during weak TCR/antigens interactions to increase T cell function triggered by weak/poorly immunogenic antigens. The results provided herein demonstrate that Mono-7D6-Fab is precisely monovalent (FIG. 10), it binds to mouse T cells but does not block peptide/MHC:TCR interactions (FIG. 11), it induces CD3Δc on its own (FIG. 12) (CD3Δc measured by the CD3-PD assay (FIGS. 3-4)), and it is functionally inert to non-antigen engaged T cells both in vitro (FIGS. 13-17) and in vivo (FIGS. 13, 18, and 19). Moreover, the administration of Mono-7D6-Fab enhanced T cell signaling induced by weak peptide/MHC antigens in vitro, as shown in experiments using T cells from the OT-I TCR transgenic mouse model (FIGS. 14-17).

Mono-7D6-Fab's capacity to increase T cell responses to weak antigens was tested in vivo using a mouse model for lung metastatic melanoma. The B16.F10 cell line is a transplantable melanoma in B6 mice that colonizes lungs when injected intra-venously (i.v.). This B16.F10 melanoma line is very aggressive and fast growing in B6 mice, and it is considered poorly immunogenic. In the absence of any specific treatment, T cells from B6 mice fail to mount productive immune responses against the natural TAAs of B16.F10 cells. A single low-dose of Mono-7D6-Fab significantly reduced melanoma burden in the lungs of B6 mice when compared with mouse IgG Fab control treated mice in six different experiments (FIG. 21). Mono-7D6-Fab anti-B16.F10 effects required the presence of T cells in B6 mice (FIG. 22), and both CD4 and CD8 T cells contribute to such effect (FIG. 23). In addition, antigenic specificity of T cells mediating Mono-7D6-Fab is required for Mono-7D6-Fab anti-tumor effects, since in mice lacking T cells specific for B16.F10 Mono-7D6-Fab failed to reduce melanoma burden (FIG. 24). These results demonstrate that Mono-7D6-Fab converted poorly stimulatory mouse TAAs of B16.F10 into efficient stimuli for B16.F10 specific CD4 and CD8 T cells among the natural B6 cell repertoire.

Example 2 Mono-7D6-Fab Promotes Therapeutic Anti-Tumor T Cell Responses in the B16F10/B6 Lung Metastatic Melanoma Model When Administered Three Days After Tumor Injection

Mice were injected intravenously with a melanoma cell line (B16F10). Three days later, half of the mice were injected intravenously with a control mouse Fab fragment (Ms IgG Fab) or Mono-7D6-Fab (10 μg/mouse). 21 days after melanoma injection, all mice were sacrificed, and lungs and peripheral lymphoid organs were collected (FIG. 25A). Pictures of the lungs were evaluated for the presence of metastatic melanoma tumor burden. Less melanoma burden was observed in mice treated with Mono-7D6-Fab (FIG. 25B). Lung pictures of each mouse in the experiment were analyzed by a software to quantify melanoma presence. A graph was prepared showing the results of melanoma density in lungs of mice treated with either Ms IgG Fab or Mono-7D6-Fab (FIG. 25C). Melanoma density in each group was statistically different (t test; ***p<0.0001), showing a reduced lung metastasis in mice that received Mono-7D6-Fab (FIG. 25C). In addition, T cells were isolated from the lung draining lymph nodes of the mice and stained for different activation markers: CD107a, CD44, and CD62L. Bar graphs were prepared, revealing the % of positive CD4 and CD8 T cells for theses markers (FIGS. 25D and 25E). The results demonstrate an increase in the percentage of CD4 and CD8 T cells being activated in mice receiving Mono-7D6-Fab (FIGS. 25D and 25E).

Example 3 Anti-melanoma effect when Mono-7D6-Fab therapy is combined with Adoptive Transfer of Melanoma Specific Cytotoxic Lymphocytes

Mice were injected intravenously with the melanoma cell line (B16F10). Three days later, half of the mice were injected intravenously with a control mouse Fab fragment (Ms IgG Fab) or Mono-7D6-Fab (10 μg/mouse). In addition, mice were injected at the same time with cytotoxic T lymphocytes (CTLs) and IL-2. IL-2 administration was repeated on days 4 and 5. The CTLs were either non-tumor specific (OT-I CTLs) or tumor specific (Pmel-1 CTLs). 28 days after melanoma injection, all mice were sacrificed, and lungs and peripheral lymphoid organs were collected (FIG. 26A). Pictures of the lungs were evaluated for the presence of metastatic melanoma tumor burden (FIG. 26B). In addition, lung pictures of each mouse in the experiment were analyzed by software to quantify melanoma presence (FIG. 26C). The results of melanoma density in lungs of mice in the four experimental groups generated in the experiment (Ms IgG Fab/OT-I CTLs, Mono-7D6-Fab/OT-I CTLs, Ms IgG Fab/Pmel-1 CTLs, and Mono-7D6-Fab/Pmel-1 CTLs) were graphed (FIG. 26D). Statistical analysis of melanoma density indicates that there was a synergistic effect against melanoma when Mono-7D6-Fab was combined with the Pmel-1 CTLs specific for the tumor but not when combined with the non-tumor specific OT-I CTLs (t test, *p<0.005**p<0.001***p<0.0001). CD8 T cells present in the mediastinal lymph node (FIG. 26D) or the lungs (FIG. 26E) of the mice engaged in this experiment were stained with the Kd-tetramer gp100 to identify cells specific for the melanoma antigen gp100. The bar graphs revealed the increase in CD8 T cell counts specific for the melanoma in the mice receiving the Mono-7D6-Fab (FIG. 26D).

Other Embodiments

It is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims. 

What is claimed is:
 1. A method for increasing an immune response against an antigen, wherein said method comprises administering a composition comprising a monovalent anti-CD3γε antibody preparation and said antigen or nucleic acid that expresses said antigen to a mammal, wherein said monovalent anti-CD3γε antibody preparation comprises Fab fragments of an anti-CD3γε antibody, and wherein said mammal produces an immune response against said antigen that is increased as compared to an immune response produced against said antigen when said antigen or said nucleic acid is administered to a comparable mammal in the absence of said monovalent anti-CD3γε antibody preparation.
 2. The method of claim 1, wherein said mammal is a human, and said Fab fragments are Fab fragments of an anti-human CD3γε antibody.
 3. The method of claim 1, wherein said Fab fragments are Fab fragments of a humanized anti-human CD3γε antibody.
 4. The method of claim 1, wherein said Fab fragments are Fab fragments of a fully human anti-human CD3γε antibody.
 5. The method of claim 1, wherein said antigen is a tumor associated antigen.
 6. The method of claim 5, wherein said tumor associated antigen is a polypeptide.
 7. The method of claim 1, wherein said antigen is within an extract from a whole tumor cell lysate.
 8. The method of claim 1, wherein said method comprises administering said antigen to said mammal.
 9. The method of claim 1, wherein said method comprises administering said nucleic acid to said mammal. 